Document U.S. Pat. No. 3,977,631 discloses a device for braking/driving an aircraft wheel, which device is mounted on an undercarriage axle. The device comprises:                a stack of disks comprising a first series constrained in rotation with the wheel and a second series, alternating with the first, and constrained in rotation with a torsion tube;        a support member mounted to rotate on the axle and constrained in rotation with the torsion tube;        brake actuators carried by the support member to press the disks together, selectively; and        a drive motor for selectively driving the support member in rotation.        
In the embodiment described in that document, the actuators are of the hydraulic type and they are powered by hydraulic pipework terminating on a stationary portion of the device. Channels are arranged in the support member leading firstly to the actuators and secondly to a space between the stationary portion and the support member, which space is sealed in leaktight manner by rotary gaskets, such that the actuators are powered hydraulically regardless of the angular position of the assembly comprising the support member and the torsion tube.
In order to brake the wheel, the support member is initially prevented from rotating, and the actuators are powered with pressure so as to press the disks together in order to generate friction between the disks of the first series and the disks of the second series. Since the disks of the second series are stationary in rotation, this serves to brake the wheel.
In contrast, in order to drive the wheel in rotation, pressure is fed to the actuators in order to press the disks together so as to create friction between the disks of the first series and the disks of the second series. Then the support member is rotated by means of the drive motor, thereby causing the torsion tube to rotate, and thus causing the second series of disks to rotate, thereby driving the wheel in rotation.
The drawbacks associated with using rotary gaskets are known, in particular wear and pollution of the gaskets from the carbon dust coming from friction between the disks. In particular, in the device shown, deformation between the stationary portion and the facing support member can be considerable, and it can be difficult to ensure that the space between the stationary portion and the support member is indeed leaktight.
The invention provides a device that is similar but that makes use of electromechanical actuators. An immediate transposition of the teaching of document U.S. Pat. No. 3,977,631 would lead to arranging electromechanical actuators on the support member, said actuators being powered by means of electrical connectors that accommodate the rotary movement between the stationary portion and the support member. However such movement makes powering actuators electrically much more complicated.